Doxycycline Pharmacology


About Doxycycline
Tetracycline Derivative, Antibiotic.
Mechanism of Action of Doxycycline
Doxycycline is a broad spectrum antibiotic which acts against both gram positive and gram negative organisms. It exerts its bacteriostatic action by accumulating inside the bacteria through specific transporter protein and by passive diffusion & inhibits bacterial protein synthesis by attaching to 30 S subunit of bacterial ribosome (which are absent in mammals).Doxycycline interfering the attachment of aminoacyl-tRNA to the mRNA-ribosome complex and peptide chain fails to grow. It chelates cations like Ca &Mg and inhibits functioning of various enzymes & ribosome.
Doxycycline is used in some areas for the treatment of Chloroquine-resistant falciparum malaria
Pharmacokinets of Doxycycline
Absorption: Orally well absorbed, food has not much effect on absorption.
Distribution: Widely distributed; shows protein- binding.
Metabolism: Not substantially metabolized inside the body.
Excretion: Primarily excreted through faeces. Some drug is present in breast milk & a portion is excreted through urine.
Onset of Action for Doxycycline
4 to 12 hours
Duration of Action for Doxycycline
24 hours
Half Life of Doxycycline
18 to 24 hours
Side Effects of Doxycycline
1. Photo toxicity
2. Intracranial hypertension
3. Dysphagia
4. Nausea
5. Vomiting
6. Epigastric distress
7. Super infection
8. Skin rashes
9. Pericarditis
10. Neutropenia
11. Elevated liver enzymes
12. Discoloration of teeth
13. Esophageal ulceration
14. Glossitis
15. Thrombocytopenia
16. Retardation of bone growth
Contra-indications of Doxycycline
1. Hypersensitivity to the drug or other tetracyclines
Special Precautions while taking Doxycycline
1.Renal impairment
2.Hepatic impairment
3.Sun exposure may leads to photo toxicity.
4.Alcohol uptake may decrease antibiotic effect.
Pregnancy Related Information
Old Age Related Information
Use with caution
Breast Feeding Related Information
Children Related Information
NEONATES : Contraindicated
Indications for Doxycycline
1. Syphilis
2. Lympho granuloma veneram
3. Typhus fever
4. Respiratory tract infections
5. Prophylaxis of malaria
6. Urinogenital tract infections
7. Trachoma
8. Pelvic inflammatory diseases
9. Acne
10. Diarrhoea
11. Gonorrhea in penicillin allergic individuals
12. Pneumonia
13. Rickettsial infections
14. Urethritis
15. Anthrax
Interactions for Doxycycline
Antacids (aluminium, calcium zinc, magnesium), Iron salts, Bismuth salts: Impair absorption of tetracyclines thus reducing its efficacy.
Anticoagulants: Increase the hypothrombinemic effects of anticoagulants.
Cimetidine: Decreases GI absorption leading to decreased efficacy of tetracyclines.
Digoxin: Increased serum levels leading to digoxin toxicity.
Methoxyflurane: Nephrotoxic effects of both increased.
Oral contraceptives: Breakthrough bleeding, pregnancy due to decreased efficacy.
Penicillins: Efficacy reduced.
Food: Dairy products decrease efficacy of tetracyclines.
Lab Tests: Bacteriosuppressive levels of Demeclocycline persist in both urine and blood for several days after cessation of therapy interfering with culture studies.

Typical Dosage for Doxycycline
Adults: 0.2gm initial dose followed by 0.1gm once daily.
In severe infections: 0.1gm 12 hourly up to 10 days.
Malaria: 200 mg daily for at least 7 days after treatment with quinine.
Malaria prophylaxis: Doxycycline 100 mg daily.
Anthrax: 200 mg / day in 2 divided doses
Acne: 100mg/day Or 50mg twice daily.
Urethritis: 100 mg twice a day for 7 days
Children (above 8 years of age): 3 to 5 mg/kg/day in two divided doses.

Schedule of Doxycycline
Storage Requirements for Doxycycline
Store in a cool place.
Effects of Missed Dosage of Doxycycline
Take the missed dose as soon as noticed and if it is the time to take the next dose then skip the missed dose.
Effects of Overdose of Doxycycline
Treatment is supportive & symptomatic. Drug can be removed by gastric lavage.

Home Delivery for Doxycycline in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including doxycycline.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for doxycycline and other medicines and health products. Home delivery services for doxycycline may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take doxycycline only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for doxycycline before they complete the sale. You can get this information while placing the order for doxycycline with the pharmacy.

Doxycycline is a generic medicine name and there are several brands available for it. Some of the brands for doxycycline might be better known than doxycycline itself. If the pharmacy that's willing to deliver medicines to your home doesn't have doxycycline in stock, you can ask for one of the branded alternatives for doxycycline.